Determination of Road-Load Constants by Coast Down Test Method [TED 4: Automotive Braking Systems]
Total Page:16
File Type:pdf, Size:1020Kb
इंटरनेट मानक Disclosure to Promote the Right To Information Whereas the Parliament of India has set out to provide a practical regime of right to information for citizens to secure access to information under the control of public authorities, in order to promote transparency and accountability in the working of every public authority, and whereas the attached publication of the Bureau of Indian Standards is of particular interest to the public, particularly disadvantaged communities and those engaged in the pursuit of education and knowledge, the attached public safety standard is made available to promote the timely dissemination of this information in an accurate manner to the public. “जान का अधकार, जी का अधकार” “परा को छोड न 5 तरफ” Mazdoor Kisan Shakti Sangathan Jawaharlal Nehru “The Right to Information, The Right to Live” “Step Out From the Old to the New” IS 14785 (2000): Automotive Vehicles - Determination of Road-load Constants by Coast Down Test Method [TED 4: Automotive Braking Systems] “ान $ एक न भारत का नमण” Satyanarayan Gangaram Pitroda “Invent a New India Using Knowledge” “ान एक ऐसा खजाना > जो कभी चराया नह जा सकताह ै”ै Bhartṛhari—Nītiśatakam “Knowledge is such a treasure which cannot be stolen” IS14785:2000 Indian Standard AUTOMOTIVE VEHICLES -- DETERMINATION OF ROAD-LOAD CONSTANTS BY COAST DOWN TEST METHOD ICS 19.060; 43.020 0 B;S 2000 BUREAU OF INDIAN STANDARDS MANAK BHAVAN, 9 BAHADUR SHAH ZAFAR MARG NEW DELHI 110002 :May 2000 Price Group 3 Automotive Vehicle Testing and Performance Evaluation Sectional Committee, TED 8 FOREWORD This Indian Standard was adopted by the Bureau of Indian Standards. after the draft finalized by-lhc Automotive Vehicle Testing and Performance Evaluation Sectional Committee had been approved by the Transport Engineering Division Council. The road-load constants of an automotive vehicle are needed for evaluation of the performance of an automotive vehicle such as fuel consumption, emission, etc, on a chassis dynamometer. Thcsc constants are used lo determine the ( load on the chassis dynamometer to simulate the power needed to propel the vchiclc at diffcrcnt speeds as per lhe appropriate driving cycle. This standard has beenprepared with a view to have a uniform procedure to be followed by the automobile manufacturers as well as the testing laboratories who. at present in the absence of this standard. have evolved their own practices for evaluating these constants. The composition of the Committee rcsponsiblc for formulating this standard is given in Annex A IS 14785 : 2000 Indian Standard AUTOMOTIVE VEHICLES -DETERMINATION OF ROAD-LOAD CONSTANTS BY COAST DOWN TEST METHOD 1 SCOPE 4 VEHICLE PREPARATION 1.1 This standard specifies the procedure for 4.1 The vehicle shall be clean and complete in all determining the equation of road-load resistance of respects, representative of production series. vehicle, including the aerodynamic and rolling 4.2 Vehicle shall be run-in as per manufacturer’s resistance by coast down technique. This data is recommendation. primarily intended for the road-load simulation on variable load curve chassis dynamometer. 4.3 The wheels of vehicle shall be free and without any parasitic drag. For vehicles with rear chain drive, This equation is expressed as F = u+6v2, where factors it shall be-ensured that there is no chain rubbing. a and b are the constants. 4.4 The weight of testing personnel riding the vehicle 1.2 However, it may be borne in mind that use of and instrumentation carried on the vehicle shall be each of these constants independently may not be part of vehicle weight ( see 8.2.1). Additional loads accurate. For example, the coefilcient ofrolling resistance may be addedto bring the actual weight during testing ‘a’ will not be accurate enough to use as a comparison to be within f 2 percent of specified weight. The of rolling resistance of tyre. distribution of weight among axles shall be as close 2 REFERENCES as possible to the values recommended by the mamiW~~ However, ifsumofmaximumrnded The following standards contain provisions which axle weights exceeds the gross vehicle weight, the through reference in this text, constitute provision of actual weight on the axle shall be in the same proportion this standard. At the time of publication, the editions of the ratios of the gross vehicle weight to the sum of indicated were valid. All standards are subject to maximum recommended axle weights. The actual load revision. and ~parties to agreements based on this condition and wheel reactions shall be recorded in standard are encouraged to investigate the possibility the report. of applying the most recent editions of the standards 4.5 Tyres which have covered only 10 ~percent or indicated below: less of their expected life shall befitted on the vehicle. IS No. Title The tread depth measurement method or tread wear indicators on the tyre may be used to assess tyre life. 9211: 1979 Denomination and definitions of At the start of the test, tyres shall be cold and shall weights of road vehicles be inflated to pressure specified for respective load 11422: 1986 Terms and definitions of weights of condition of the vehicle. two wheeled motor vehicles 4.6 The grade, quality, quantity of lubricants for various 3 DEFINITIONS moving parts, adjustments ofbrake, clutch, idling speed, etc, shall conform to the man-r ‘s recommendation. The vehicle may be serviced before the test wasper 3.1 LadenVehicle the procedure recommended by manufacturer. A vehicle loaded to the condition of weight required 5 FEATURES OF TEST TRACK for-establishing the road-load. The test shall be conducted on a dry, level test track NOTE - The load condition of the vehicle for which the road-load equation is to be determined, depends on with a coefficient of adhesion not less than 0.8, the end use of this equation. For example, for emission particularly in region where the test is to be conducted. measurement for statutory purposes, the load condition If test surface is of tar, it shall not be traffic smooth is the ‘Reference Mass’, whereas for design verification and surface shall not have become soft due to heat. tests, it may be the ‘Gross Vehicle Weight’. Longitudinal slope of the track shall-not exceed 3.2 Unladen Vehicle 0.5 percent and shall be constant within f 0.1 percent over the measuring strip. The track shall have sufbcient A vehicle in the condition of kerb weight as per the length and width for achieving the test speed and relevant Indian Standard, given in 2 above. carrying out the test safely. 1 IS 14785 : 2000 6 INSTRUMENTATION 8 COAST DOWN TEST 6.1 Fitment of instruments shall be as recommended 8.1 General by instrument manufacturer. All instruments and the 8.1.1 Coast down test for a specific test speed (v) is additional weights, if any, shall be mounted in such a basically to establish the road-load ‘F’ from the way that they do not affect the performance or stability deceleration by measuring time elapsed from speed of the vehicle and do not hamper rider/driver from ‘v + 6v’ to speed ‘v - Sv’, when the transmission is in normal driving of vehicle and carrying out tests. The neutral. From the values of ‘F at different speeds, instrument shall be positioned on the vehicle such values of constants ‘a’ and ‘b ’ in equation F = a + bv* that it does not significantly affect the aerodynamics are determined by best curve fit method. of the vehicle. 8.1.2 In the case of two wheelers, the recommended 6.2 Calibration of instrument shall be checked and height of rider shall be 1.7 f 0.05 m and the rider shall adjusted asper instrument manufacturer’s instructions wear helmet and proper riding gear. He shall be seated before commencement of test. upright on the seat provided for the rider, his feet upon the pedals or foot rests. This position shall, 6.3 Automatic speed and distance measuring nevertheless, allow the rider at all times to have proper instruments meeting following least count and accuracy control of the vehicle during the test. requirements shall be used. 8.1.3 While carrying out the test, the portion of the Parameter Least Count Accuracy test track where the vehicle is decelerated from ‘v + 6v’ to ‘v - 6~’ shall be kept approximately same in Speed O.lkmh O.lkm/h both directions to reduce the effect of track variation. This shall be followed for each test speed. Distance O.lm O.lm 8.1.4 Forimproving the consistency of the test results, Time 0.01 s 0.01 s it is preferable that : *’ 7 TEST REQUIREMENTS a) the test at all speeds is conducted by the same 7.1 The test shall be conducted when wind speed is rider/ driver. less than 3 m/s with~gusts less than 5 m/s. In addition, b) the test at each speed shall be done continuously the vector component across the test-road shall not without intermediate stoppage. be more than 2 m/s. The wind velocity measurement shall be done at a height of 0.7 m above the road 8.2 Testing Procedure surface. The ambient temperature shall be preferably 8.2.1 The test shall be conducted with the load condition between 15” to 40°C -and relative humidity shall given in 3.1. preferably be less than 75 percent. 8.2.2 Test Speeds NOTE -~ For proper consistency of test results, it is preferred that the tests are done with wind velocity less a) The test shall be conducted at least at 5 speeds.